This invention relates generally to a new method for preparing esters of thienylglyoxylic and thienylacetic acids.
Methods are known for a long time for preparing glyoxylic esters of thiophenic derivatives. Nevertheless, the results which were obtained were rather poor. Such methods are described, amongst others in: Bradley Ber, 19-2119 (1886), Steinkopf & Wolfram, Ann. 437,22 (1824), Blicke & Tsao, Jacs, 66, 1645 (1944), and more recently the French Pat. Nos. 2.068.425 (1969), 2.113.760 (1970) and 2.167.334 (1972).
In view of the increasing use of these products, such methods are too expensive and cannot allow the production of product with constant quality and with a sufficient yield.